Add support for Spotify (squashed commit), and:

- Try to not return items which a client can't play
    - Remove inotify subscription to IN_MODIFY and IN_CREATE
    - Fix crash on unknown codec type in transcode.c
    - Probably added some new bugs...

src/player.h

@@ -33,6 +33,11 @@ enum repeat_mode {
   REPEAT_ALL  = 2,
 };
 
+enum source_type {
+  SOURCE_FFMPEG = 0,
+  SOURCE_SPOTIFY = 1,
+};
+
 struct spk_flags {
   unsigned selected:1;
   unsigned has_password:1;
@@ -60,6 +65,9 @@ struct player_source
 {
   uint32_t id;
 
+  enum source_type type;
+  int setup_done;
+
   uint64_t stream_start;
   uint64_t output_start;
   uint64_t end;